Hot-water boiler for hot-water heating mat

ABSTRACT

Disclosed herein is a hot-water boiler for a hot-water heating mat. The boiler is configured such that a high-temperature space and a low-temperature space, respectively, located on left and right sides of a recess formed in a lower portion of a central region of a hot-water heating tank, a discharge space connecting upper portions of the high-temperature space and the low-temperature space with each other, and a hot-water heating pipe connecting lower portions of the high-temperature space and the low-temperature space with each other are arranged to form a ‘ ’-shaped circulation path. The hot-water heating pipe is inclined and an electric heater is provided on an outer surface of the hot-water heating pipe.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a hot-water boiler for a hot-water heating mat. More particularly, the present invention relates to a hot-water boiler for a hot-water heating mat, in which a high-temperature space and a low-temperature space, respectively, located on left and right sides of a recess formed in a lower portion of a central region of a hot-water heating tank, a discharge space connecting upper portions of the high-temperature space and the low-temperature space, with each other, and a hot-water heating pipe connecting lower portions of the high-temperature space and the low-temperature space with each other are arranged to form a ‘

’-shaped circulation path, the hot-water heating pipe is inclined and an electric heater is provided on an outer surface of the hot-water heating pipe, so that a small amount of water in the hot-water heating tank is instantaneously vaporized using the hot-water heating pipe having on the outer surface thereof the electric heater, a small, amount of hot water is moved to the hot-water storage tank by the vapor pressure, and a small amount of water in the hot-water heating mat is drawn by vacuum suction force that is generated in the hot-water heating tank in proportion to the volume of moved water, thus allowing a small amount, of hot water to be continuously circulated in a short cycle and drastically enhancing hot-water circulation efficiency as compared to a conventional hot-water boiler configured such that all water in the hot-water hearing tank is heated to generate vacuum suction force.

2. Description of the Related Art

Generally, a hot-water heating mat refers to a heating mat configured such that a hot-water hose in which hot water is circulated is accommodated in a mat body, and a heating operation is performed by hot water supplied by a small-sized hot-water boiler connected with the mat body via a connecting hose.

Such a hot-water heating mat is advantageous in that it solves a problem occurring in the conventional electric mat configured such that an electric heating wire is accommodated in the mat body. In other words, the hot-water heat mat completely eliminates the risk of fire or electric shocks due to harmful electromagnetic waves and electric heating wires.

However, the hot-water boiler, which is widely used in conventional hot-water heating mats, mainly employs an electric motor pump to circulate hot water heated by an electric heater. Such a hot-water boiler for the hot-water heating mat is problematic in that durability is considerably deteriorated due to the frequent failure of the electric motor pump that is operated in a hot-water environment, and in that, noise and vibration generated when the electric motor pump is driven may be transmitted to the outside without being reduced, thus causing unpleasant, noise and disturbing a user's sleep.

Further, the conventional hot-water boiler for the hot-water heating mat is problematic in that, when the hot-water hose of the hot-water heating mat is folded or the connecting hose is bent due to a user's carelessness, so that the circulation of the hot water is blocked, the electric motor pump circulating the hot water is overloaded and thereby durability is considerably lowered.

In order Co solve the problems, a hot-water boiler for a hot-water heating mat has been proposed, in which the mat is configured to circulate hot water therein using vapor pressure generated in a hot-water heating tank when hot water is heated. However, such a natural-circulation-type hot-water boiler using the vapor pressure is problematic in that, when the hot-water hose of the hot-water heating mat is folded or the connecting hose is bent due to a user's carelessness and the circulation of the hot water is blocked, the hot-water boiler may undesirably explode due to the excessive vapor pressure.

In order to overcome the problems of the natural-circulation-type hot-water boiler using the vapor pressure, the inventor(s) invented a hot-water boiler for a hot-water heating mat configured to circulate hot water in a hot-water heating mat using vacuum suction force. This invention was registered in Korean Patent Kos. 0918522, 0948908, and 1418947.

The hot-water boiler for the hot-water heating mat that was previously filed by the applicant of the present invention is configured as follows: a hot-water storage tank is connected to a hot-water heating tank in which an electric heater is accommodated, so that, when hot water is heated by the electric heater, hot water generated in the hot-water heating tank is moved to the hot-water storage tank by vapor pressure generated in the hot-water heating tank. At this time, water present in the hot-water heating mat is circulated using the vacuum suction force generated in the hot-water heating tank.

However, the conventional hot-water boiler for the hot-water heating mat configured as such is problematic in that all of about 150 to 200 ml of water present in the hot-water heating tank is heated and discharged to generate vacuum suction force in the hot-water heating tank, so that about one to two minutes are required to generate the vacuum suction force in the hot-water heating tank depending on the volume of the hot-water heating tank, and the hot water is circulated in a cycle of about one to two minutes, with the result that water present in the hot-water heating mat may get cold during the above-mentioned cycle and circulation efficiency may be considerably deteriorated.

In order to solve the problems, a method of significantly increasing the volume of the hot-water heating tank to entirely circulate water in the hot-water heating mat has been proposed. However, this method is problematic in that the capacity of the electric heater may be excessively increased, and water boiling noise and power consumption may foe undesirably increased. Therefore, the conventional method has a limit in improving the circulation efficiency.

DOCUMENTS OF RELATED ART

-   (Patent Document 1) Korean Patent No. 10-0918522 -   (Patent Document 2) Korean Patent No. 10-0948908 -   (Patent Document 3) Korean Patent No. 10-1416947

SUMMARY OF THE INVENTION

Accordingly, the present invention has been made keeping in mind the above problems occurring in the related art, and an object of the present invention is to provide a hot-water boiler for a hot-water heating mat, in which, a high-temperature space and a low-temperature space, respectively, located on left and right sides of a recess formed in a lower portion of a central region of a hot-water heating tank, a discharge space connecting upper portions of the high-temperature space and the low-temperature space with each other, and a hot-water heating pipe connecting lower portions of the high-temperature space and the low-temperature space with each other are arranged to form ‘

’-shaped circulation path, the hot-water heating pipe is inclined and an electric heater is provided on an outer surface of the hot-water heating pipe, so that a small amount of water in the hot-water heating tank is instantaneously vaporized using the hot-water heating pipe having on the outer surface thereof the electric heater, a small amount of hot water is moved to the hot-water storage tank by the vapor pressure, and a small amount of water in the hot-water heating mat is drawn by vacuum suction force that is generated in the hot-water heating tank in proportion to the volume of moved water, thus allowing a small amount of hot water to be continuously circulated in a short cycle and drastically enhancing hot-water circulation efficiency as compared to a conventional hot-water boiler configured such that all water in the hot-water heating tank is heated to generate vacuum suction force.

In order to achieve the above object, according to one aspect of the present invention, there is provided a hot-water boiler for a hot-water heating mat, including a hot-water heating tank having an electric heater to heat water therein, a hot-water outlet port provided on an inner portion of an upper surface thereof, and a hot-water recovery port provided at a position of a lower portion thereof and connected to the hot-water heating mat, with a water-level sensor provided therein; a hot-water storage tank connected with the hot-water heating tank, and having a water replenishment hole provided at a position, on an outer portion thereof to be open or closed by a stopper, a hot-water inlet pore provided at another position on the outer portion, thereof to be connected with, the hot-water outlet port of the hot-water heating-tank, and a hoc-water supply port connected with the hot-water heating mat, with a water-shortage detection sensor provided therein; and a check valve for discharge, the check valve being provided in the hot-water inlet port of the hot-water storage tank, wherein the hot-water heating tank is configured such that a high-temperature space and a low-temperature space, respectively, located on left and right sides of a recess formed in a lower portion of a central region of the hot-water heating tank, a discharge space connecting upper portions of the high-temperature space and the low-temperature space with each other, and a hot-water heating pipe connecting lower portions of the high-temperature space and the low-temperature space with each other are arranged to form a ‘

’-shaped circulation path, wherein the hot-water heating pipe is inclined, and the electric heater is provided on an outer surface of the hot-water heating pipe to instantaneously vaporize a small amount of water in the hot-water heating pipe.

Further, a check valve for recovery may be provided in the hot-water recovery port of the hot-water heating tank.

A plurality of heat radiation fins may be formed on an inner circumference of the hot-water heating pipe provided in the hot-water heating tank to extend in a longitudinal direction.

A silencing cover having on an end thereof a bubble trap step may be provided on an end of the hot-water heating pipe provided in the hot-water heating tank.

A bubble guide wall may be provided on an inner surface in the upper portion of the high-temperature space defined, in the hot-water heating tank to guide bubbles generated in the hot-water heating pipe to an upper portion of the discharge space.

An air vent hole may be formed in the hot-water outlet port provided in the discharge space of the hot-water heating tank to communicate with the hot-water inlet port of the hot-water storage tank.

An air discharge hole may be formed in the stopper for opening or closing the water replenishment hole of the hot-water storage tank, and an air discharge tube may be provided in the hot-water storage tank to be connected with the air discharge hole of the stopper.

An auxiliary space may be formed in an upper portion of the hot-water storage tank to be at a higher position than the water replenishment hole.

As is apparent from the above description, a hot-water boiler for a hot-water heating mat according to the present invention is advantageous in that a high-temperature space and a low-temperature space, respectively, located, on left and right sides of a recess formed in a lower portion of a central region of a hoc-water heating tank, a discharge space connecting upper portions of the high-temperature space and the low-temperature space with each other, and a hot-water heating pipe connecting lower portions of the high-temperature space and the low-temperature space with each, other are arranged to form a ‘

’-shaped circulation path, the hot-water heating pipe is inclined and an electric heater is provided on an outer surface of the hoc-water heating pipe, so that a small amount of water in the hot-water heating tank is instantaneously vaporized using the hot-water heating pipe having on the outer surface thereof the electric heater, a small amount of hot water is moved to the hot-water storage tank by the vapor pressure, and a small amount of water in the hot-water heating mat is drawn by vacuum suction force that is generated in the hot-water heating tank in proportion to the volume of moved water, thus allowing a small amount of hot water to be continuously circulated in a short cycle and drastically enhancing hot-water circulation efficiency as compared, to a conventional hot-water boiler configured such that all water in the hot-water heating tank is heated to generate vacuum suction force.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features, and advantages of the present, invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a perspective view illustrating the use of a hot-water boiler for a hot-water heating mat according to the present invention;

FIG. 2 is a sectional view illustrating the configuration of principle parts of the hot-water boiler for the hot-water heating mat according to the present invention;

FIG. 3 is an enlarged view portion “A” encircled, in FIG. 2;

FIG. 4 is a sectional view illustrating the structure of a hot-water heating pipe provided in the hot-water boiler for the hot-water heating mat according to the present invention;

FIGS. 5A and 5B are sectional views illustrating an instantaneous heating process and a bubble discharge process by the hot-water heating pipe provided in the hot-water boiler for the hot-water heating mat according to the present invention;

FIGS. 6A and 6B are sectional views illustrating a water-level regulating process by an auxiliary space provided in the hot-water boiler for the hot-water heating mat according to the present invention; and

FIGS. 7A to 7D are views illustrating the operation of the hot-water boiler for the hot-water heating mat according to the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

Hereinbelow, the preferred embodiment of the present invention will be described in detail with reference to FIG. 1 to FIGS. 7A to 7D.

As shown in FIG. 2, a hot-water boiler for a hot-water heating mat according to the present invention includes a hot-water heating tank 2, a hot-water storage tank 10, and a check valve 13 a for discharge.

The hot-water heating tank 2 is configured to instantaneously vaporize a small amount of water filled in a hot-water heating pipe 6 via an electric heater 7 exposed to an outside, discharge a small amount of hot water to the hot-water storage tank 10 by vapor pressure, and draw a small amount of water from an interior of the hot-water heating mat by vacuum suction force that is generated in proportion to the volume of discharged water. The hot-water heating tank includes a recess 2 a in a lower portion of a central, region thereof to have an inverted ‘

’shape. A high-temperature space 4 and a low-temperature space 5 are provided on left and right sides of the recess 2 a. A discharge space 3 connects upper portions of the high-temperature space 4 and the low-temperature space 5 with each other. The hot-water heating pipe 6 connects lower portions of the high-temperature space 4 and the low-temperature space 5 with each other. These components are arranged to define a ‘

’-shaped circulation path.

If the hot-water heating tank 2 is configured to define the ‘

’-shaped circulation path, convection circulation may be more smoothly performed, in which water heated in the hot-water heating pipe 6 passes through the high-temperature space 4, moves upwards to the discharge space 3, meets cold water in the low-temperature space 5, and moves downwards to return to the hot-water heating pipe 6. Therefore, water contained in the hot-water heating tank 2 may be more efficiently heated by the electric heater 7 exposed to the outside, and bubbles generated when the small amount of water is instantaneously vaporized in the hot-water heating pipe 6 may be more rapidly moved to the discharge space 3.

The discharge space 3 defined in the upper portion of the hot-water heating tank 2 is intended to discharge hot water from the hot-water heating tank 2. A hot-water outlet port 8 is provided on an inner surface of the upper portion of the discharge space, and a water-level sensor 3 a is provided in the hot-water heating tank.

The high-temperature space 4 defined on one side under the discharge space 3 is a space where hot water generated in the hot-water heating pipe 6 stays. The low-temperature space 5 defined on the other side under the discharge space 3 is a space where cold water drawn, from the hot-water heating mat stays, with a hot-water recovery port S being provided at a position in the low-temperature space to be connected with the hot-water heating mat.

A check valve 9 a for recovery may be provided in the hot-water recovery port 9. The check valve 9 a for recovery serves to move hot water contained in the hot-water heating mat to the interior of the hot-water heating tank 2 and to prevent hot water generated in the hot-water heating tank 2 from flowing backwards to the hot-water heating mat.

The water-level sensor 3 a provided in the discharge space 3 of the hot-water heating tank 2 serves to detect that the water level of the hot-water heating tank 2 falls below a lower end of the hot-water outlet port 8. The water-level sensor usually employs a known float-type water-level sensor or electronic water-level sensor, which is commonly used in a humidifier or an aquarium. As the hot-water boiler becomes slim, the interior of the hot-water heating tank 2 becomes smaller and smaller. Therefore, in order to easily install the water-level sensor in the small hot-water heating tank, it is preferable to employ the electronic water-level sensor that is smaller in volume and occupies less space than the float-type water-level sensor.

As shown in FIG. 3, an air vent hole 8 a is preferably formed in the hot-water outlet port 8 provided in the discharge space 3 of the hot-water heating tank 2 to communicate with the hot-water inlet port 13 of the hot-water storage tank 10.

If the air vent hole 8 a is formed in the hot-water outlet port 8 as such, air may be automatically discharged through the air vent hole 8 a formed in the hot-water outlet port 8 to the hot-water inlet port 13 of the hot-water storage tank 10 even if air flows into the hot-water heating tank 2.

The hot-water heating pipe 6 connected between the high-temperature space 4 of the hot-water heating tank 2 and the low-temperature space 5 thereof serves to instantaneously vaporize a small amount of water, with the electric heater 7 provided, on an outer surface of the hot-water heating pipe, The electric heater 7 provided on the outer surface of the hot-water heating pipe 6 as such may instantaneously vaporize only a small amount of water in the hot-water heating pipe 6 that makes contact with the electric heater 7, unlike a conventional hot-water boiler in which an electric heater is provided in a hot-water heating tank, an entire amount of water in the hot-water heating tank is heated, and thereby it is impossible to instantaneously vaporize only a small amount of water.

Further, the hot-water heating pipe 6 is arranged to be inclined. That is, the hot-water heating pipe is preferably inclined upwards to the high-temperature space 4 to allow the bubbles generated, in the hot-water heating pipe 6 to be smoothly discharged through the high-temperature space 4 to the discharge space 3 when a small amount of water in the hot-water heating pipe 6 is instantaneously heated by the electric heater 7 installed outside the hot-water heating pipe 6.

Preferably, the hot-water heating pipe 6 is made of a material having high heat conductivity, for example, aluminum, to allow neat generated in the electric heater 7 to be smoothly transferred to water that passes through the hot-water heating pipe 6.

As shown in FIG. 4, a plurality of heat radiation fins 6 a is preferably formed on the inner circumference of the hot-water heating pipe 6 to extend in a longitudinal direction.

If the plurality of heat radiation fins 6 a is formed on the inner circumference of the hot-water heating pipe 6 to extend, in the longitudinal direction, the heat source generated in the electric heater 7 may be more smoothly transferred to water in the hot-water heating pipe 6, so that heat transfer efficiency may be drastically increased, and the strength of the pipe-shaped hot-water heating pipe 6 is increased, with the result that the thermal strain of the hot-water heating pipe 6 may be minimized due to the heat emission of the electric heater 7.

Preferably, a silencing cover 16 having on an end thereof a bubble trap step 16 a is provided on an end of the hot-water heating pipe 6.

If the silencing cover 16 having the bubble trap step 16 a is provided on the end of the hot-water heating pipe 6, as shown in FIG. 5A, when the small amount of water contained in the hot-water heating pipe 6 is instantaneously vaporized by the electric heater 7 provided outside of the hot-water heating pipe 6, the bubbles generated in the hot-water heating pipe 6 do not burst upon entire discharge, but burst while being discharged gradually after being trapped by the bubble trap step 16 a of the silencing cover 16 provided on the end of the hot-water heating pipe 6, so that it is possible to drastically reduce noise made during the bubble generation, namely, water boiling noise.

In addition, a round- or slope-shaped bubble guide wail 4 a is provided on an inner surface in the upper portion of the high-temperature space 4 defined in the hot-water heating tank 2 to guide bubbles generated in the hot-water heating pipe 6 to the upper portion of the discharge space 3.

If the bubble guide wall 4 a is provided on the inner surface in the upper portion of the high-temperature space 4 defined in the hot-water heating tank 2, as shown in FIG. 5B, when the small amount of water contained in the hot-water heating pipe 6 is instantaneously vaporized by the electric heater 7 provided outside of the hot-water heating pipe 6 and is discharged through the end of the hot-water heating pipe 6, the discharged bubbles do not burst while entirely moving upwards, but burst while slowly moving upwards along the bubble guide wall 4 a, so that, it is possible to drastically reduce noise made during the bubble generation, namely, water boiling noise.

As the electric heater 7 installed outside the hot-water heating pipe 6, various types of known electric heaters may be used. Among the known electric beaters, a PTC (Positive Temperature Coefficient) thermistor is preferred. Such a heater occupies a small space for installation thus meeting the demands of a trend towards slimness of the hot-water boiler. Further, the PTC thermistor generates a very high watt heat despite a small heat transfer area, thus making it possible to instantaneously vaporize a small amount of water in the hot-water heating pipe 6.

The hot-water storage tank 10 is connected with the hot-water heating tank 2 to store hot water discharged from the hot-water heating tank 2. A water replenishment hole 11 is formed at a side of an outer portion of the hot-water storage tank to be opened or closed by a stopper 12, and the hot-water inlet port 13 connected with the hot-water outlet port 8 of the hot-water heating tank 2 and a hot-water supply port 14 connected with the hot-water heating mat are formed at the other side of the outer portion of the hot-water storage tank. A water-shortage detection sensor 15 is provided, in the hot-water storage tank.

Preferably, a stepper 12 for opening or closing the water replenishment hole 11 of the hot-water storage tank 10 may be fastened in a threaded-type fastening method with a sealing packing interposed therein, or may be firmly fastened by a locking protrusion and a locking hole.

Further, an air discharge hole 12 a may be formed in the stopper 12 to discharge air or water vapor from the hot-water storage tank 10. A U-shaped air discharge tube 17 is preferably installed in the hot-water storage tank 10 to be connected with the air discharge hole 12 a of the stopper 12.

If the U-shaped air discharge tube 17 is installed in the hot-water storage tank 10 to be connected with the air discharge hole 12 a of the stopper 12, hot water stored in the hot-water storage tank 10 is not discharged through the air discharge hole 12 a of the stopper 12 but only the air or water vapor in the hot-water storage tank 10 is easily discharged to an outside of the hot-water storage tank 10, even if the hot-water storage tank 10 is filled with hot water.

Preferably, an auxiliary space 18 is formed in the upper portion of the hot-water storage tank 10 to be at a higher position than the water replenishment hole 11.

If the auxiliary space 18 is formed in the upper portion of the hot-water storage tank 10 to be at a higher position than the water replenishment hole 11, when a hot-water hose of the hot-water heating mat is pressed or a connecting hose is bent with the hot-water storage tank 10 being filled with hot water as shown in FIG. 6A, so that hot water stored in the hot-water storage tank 10 is not discharged to the hot-water heating mat and hot water discharged out from the hot-water heating tank 2 continuously flows into the hot-water storage tank 10, the auxiliary space 18 located at a higher position than the water replenishment hole 11 may receive a sufficient amount of hot water discharged out from the hot-water heating tank 2 as shown in FIG. 6B. Therefore, such a configuration prevents water from leaking out through a gap between the water replenishment hole 11 and the stopper 12 when the hot-water storage tank 10 is over-replenished.

The water-shortage detection sensor 15 installed in the hot-water storage tank 10 serves to detect a water level thereof. The water-shortage detection sensor usually employs a known float-type water-level sensor or electronic water-level sensor, which is commonly used in a humidifier or an aquarium. As the hot-water boiler becomes slim, the interior of the hot-water storage tank 10 becomes smaller and smaller. Therefore, in order to easily install the water-shortage detection sensor in the small hot-water storage tank, it is preferable to employ the electronic water-level sensor that is smaller in volume and occupies less space than the float-type water-level sensor.

The check valve 13 a for discharge is provided in the hot-water inlet port 13 of the hot-water storage tank 10, and serves to move hot water generated in the hot-water heating tank 2 to the hot-water storage tank 10 and to prevent not water stored in the hot-water storage tank 10 from flowing backwards to the hot-water heating tank 2.

Meanwhile, an electric circuit of the hot-water boiler for the hot-water heating mat according to the present invention is connected to a control board having a bimetal-type heater overheat prevention sensor and an overturn detection sensor being interposed therein. The heater overheat prevention sensor causes power to automatically be cut off when the electric heater is overheated. The overturn detection sensor cuts off the supply of power when the hot-water boiler is overturned. The water-level, sensor 3 a and the electric heater 7 provided in the hot-water heating tank 2, the water-shortage detection sensor 15 provided in the hot-water storage tank 10, a water-shortage warning light turned on when a low water level is detected in the hot-water storage tank 10, and an overheat-prevention temperature sensor attached to the tipper portion of the outside of the hot-water heating tank 2 are connected to the control board.

The operation of the hot-water boiler for the hot-water heating mat according to the present invention configured as such will be described below.

As shown in FIG. 1, the hot-water boiler for the hot-water heating mat according to the present invention is used while being connected to the hot-water heating mat 20 using a pair of connecting hoses 21 and 22. If a power switch of the hot-water boiler 1 is turned on in the state where the hot-water boiler 1 of the present invention is connected to the hot-water heating mat 20 by the pair of connecting hoses 21 and 22, the water-shortage warning light is turned on because no water is initially present in the hot-water boiler 1.

In order to inject water into the hot-water boiler 1 in such a state, as shown in FIG. 7A, the connecting hose 22 is separated from the hot-water supply port 14 formed in the lower surface of the hot-water storage tank 10 and then water is injected through an end of the separated connecting hose 22 into the hot-water heating mat 20 and the hot-water boiler 1. Here, a conventional manual water pump or a water injecting device that is specially manufactured is used as the device for injecting water into the connecting hose 22.

If water is injected through the connecting hose 22 separated from the hot-water supply port 14 of the hot-water storage tank 10, the injected water fills the hot-water hose installed in the hot-water heating mat 20 and then is introduced into the hot-water heating tank 2 through the hot-water recovery port 9 of the hot-water heating tank 2. Thus, the interior of the hot-water heating tank 2 is filled with water.

Subsequently, the connecting hose 22 separated from the hot-water supply port 14 of the hot-water storage tank 10 is connected to the hot-water supply port again, and the stopper 12 fastened to the water replenishment hole 11 formed in the upper portion of the hot-water storage tank 10 is open. Thereafter, water is injected to a predetermined water level in the hot-water storage tank 10, and thereby it is confirmed that the water-shortage warning light is turned off. Next, the stopper 12 is fastened to the water replenishment hole 11. In this manner, the water injection operation for the hot-water boiler 1 is completed.

After the water injection operation for the hot-water boiler 1 and the hot-water heating mat 20 is completed, water in the hot-water heating pipe 6 connected between the high-temperature space 4 and the low-temperature space 5 of the hot-water heating tank 2 is started by the electric heater 7 mounted on the outside of the hot-water heating pipe 6. At this time, as shown in FIG. 7B, a small amount of water present in the hot-water heating pipe 6 is instantaneously vaporized and the internal pressure of the hot-water heating tank 2 is increased. If the internal pressure of the hot-water heating tank 2 is increased as such, the vapor pressure causes a small amount of hot water generated in the hot-water heating tank 2 to be discharged through the hot-water outlet port 8 into the hot-water storage tank 10 while opening the check valve 13 a for discharge.

Subsequently, if a small amount of hot water generated in the hot-water heating tank 2 is discharged to the hot-water outlet port 8 and then the supply of power to the electric heater 7 is automatically cut off to stop operating the electric heater 7, the water vapor generated in the hot-water heating tank 2 starts to liquefy and the internal pressure of the hot-water heating tank 2 is rapidly reduced, thus creating a vacuum state. If the vacuum state is created in the hot-water heating tank 2 as such, a suction force is generated by the vacuum state. Thereby, as shown in FIG. 7C, a small amount of hot water in the hot-water heating mat 20 is drawn through the hot-water recovery port 9 of the hot-water heating tank 2 into the hot-water heating tank 2.

Here, if the vacuum state is created in the hot-water heating tank 2, the check valve 13 a for discharge is more firmly closed by the vacuum suction force and the path of the hot-water outlet port 8 is blocked, so that the hot water stored in the hot-water storage tank 10 is never drawn into the not-water heating tank 2.

As a small amount of hot water in the hot-water heating mat 20 is drawn into the hot-water heating tank 2 by the vacuum suction force generated in the hot-water heating tank 2, the vacuum state is continuously created, even in the hot-water heating mat 20. If the vacuum state is created in the hot-water heating mat 20, the suction force is generated by the vacuum state. Thereby, as shown in FIG. 7D, a small amount of hot water stored in the hot-water storage tank 7 is drawn through the hot-water supply port 14 into the hot-water heating mat 20, so that the hot water is circulated.

If the hot water in the hot-water heating mat 20 is drawn into the hot-water heating tank 2 by the vacuum suction force generated in the hot-water heating tank 2 as such, power is supplied to the electric heater 7 provided outside the hot-water heating pipe 6 by the control board, so that the electric heater 7 is operated again. Thereby, the hot-water circulation process is continuously repeated in a short cycle.

The hot-water boiler for the hot-water heating mat according to the present invention is preferably set such that a circulation amount of the hot-water heating tank 2 is in the range of 10 to 30 ml and a circulation cycle thereof is in the range of two to three seconds.

As described, above, the present invention provides a hot-water boiler for a hot-water heating mat, in which a high-temperature space 4 and a low-temperature space 5, respectively, located on left and right sides of a recess 2 a formed in a lower portion of a central region of a hot-water heating tank 2, a discharge space 3 connecting upper portions of the high-temperature space 4 and the low-temperature space 5 with each other, and a hot-water heating pipe 6 connecting lower portions of the high-temperature space 4 and the low-temperature space 5 with each other are arranged to form a ‘

’-shaped circulation path, the hot-water heating pipe 6 is inclined and an electric heater 7 is provided, on an outer surface of the hot-water heating pipe 6, so that a small amount of water in the hot-water heating tank 2 is instantaneously vaporized using the hot-water heating pipe 6 having on the outer surface thereof the electric hearer 7, a small amount of hot water is moved to the hot-water storage tank 10 by the vapor pressure, and a small amount of water in the hot-water heating mat is drawn by vacuum suction force that is generated in the hot-water heating tank 2 in proportion to the volume of moved water, thus allowing a small amount of hot water to be continuously circulated, in a short cycle and drastically enhancing hot-water circulation efficiency as compared to the conventional hot-water boiler configured such that all water in the hot-water heating tank is heated to generate vacuum suction force.

Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. 

What is claimed is:
 1. A hot-water boiler for a hot-water heating mat, comprising: a hot-water heating tank having an electric heater to heat water therein, a hot-water outlet, port provided on an inner portion of an upper surface thereof, and a hot-water recovery port provided at a position of a lower portion thereof and connected to the hot-water heating mat, with a water-level sensor provided therein; a hot-water storage tank connected with the hot-water heating tank, and having a water replenishment hole provided at a position on an outer portion thereof to be open or closed by a stopper, a hot-water inlet port provided at another position on the outer portion thereof to be connected with the hot-water outlet port of the hot-water heating tank, and a hot-water supply port connected with the hot-water heating mat, with a water-shortage detection sensor provided therein; and a check valve for discharge, the check valve being provided in the hot-water inlet port of the hot-water storage tank, wherein the hot-water heating tank is configured such that a high-temperature space and a low-temperature space, respectively, located on left and right sides of a recess formed in a lower portion of a central region of the hot-water heating tank, a discharge space connecting upper portions of the high-temperature space and the low-temperature space with each other, and a hot-water heating pipe connecting lower portions of the high-temperature space and. the low-temperature space with each other are arranged to form a ‘

’-shaped circulation path, wherein the hot-water heating pipe is inclined, and the electric heater is provided on an outer surface of the hot-water heating pipe to instantaneously vaporize a small, amount of water in the hot-water heating pipe.
 2. The hot-water boiler as set forth in claim 1, wherein a check valve for recovery is provided, in the hot-water recovery port of the hot-water heating tank.
 3. The hot-water boiler as set forth in claim 1, wherein a plurality of heat radiation fins is formed on an inner circumference of the hot-water heating pipe provided in the hot-water heating tank to extend in a longitudinal direction.
 4. The hot-water boiler as set forth in claim 1, wherein a silencing cover having on an end thereof a bubble trap step is provided on an end of the hot-water heating pipe provided in the hot-water heating tank.
 5. The hot-water boiler as set forth in claim 1, wherein a bubble guide wail is provided on an inner surface in the upper portion of the high-temperature space defined in the hot-water heating tank to guide bubbles generated in the hot-water heating pipe to an upper portion of the discharge space.
 6. The hot-water boiler as set forth in claim 1, wherein an air vent hole is formed, in the hot-water outlet port provided in the discharge space of the hot-water heating tank to communicate with the hot-water inlet port of the hot-water storage tank.
 7. The hot-water boiler as set forth in claim 1, wherein an air discharge hole is formed in the stopper for opening or closing the water replenishment hole of the hot-water storage tank, and an air discharge tube is provided in the hot-water storage tank to be connected with the air discharge hole of the stopper.
 8. The hot-water boiler as set forth in claim 1, wherein an auxiliary space is formed in an upper portion, of the hot-water storage tank to be at a higher position than the water replenishment hole. 